Method, set, and apparatus for obtaining prints of a part of the human body

ABSTRACT

Apart of a human body is caused to contact the surface layer of a recording medium over which a plurality of metallic grains with an outside size of 200 nm or less are distributed. Then, secretions from the skin surface of the body part are caused to adhere to the surface layer of the recording medium to take the print of the body part. If light is irradiated to the recording medium, specific optical characteristics resulting from the surface structure of the recording medium are obtained, and therefore the color of the recording medium varies between a region having secretions and a region having no secretions. This renders it possible to record a visible print on the recording medium.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of obtaining prints of theshape or patterns of a part of the human body, such as a handprint, afootprint, a fingerprint, etc., and to a set and apparatus for obtainingsuch prints by the method.

2. Description of the Related Art

Human handprints and footprints are taken as a record of a child'sgrowth or as a proof of a celebrity's visit and they are left incommemoration. Also, fingerprints are sometimes employed to identify aperson. The print of a hand or a foot is usually taken by applying inkor India ink to the hand or foot and then impressing it on coloredpaper. Recently, a handprint or footprint impressed on paper has beenread by a scanner and stored or reproduced as digital data (see JapaneseUnexamined Patent Publication No. 2002-314795). In the case of thefingerprints, the digital data is sometimes utilized to checkfingerprints.

However, in the aforementioned conventional method, it is necessary towash ink or India ink left on a hand or foot after the print of the handor foot is taken, so it is difficult to take the print of a part of thehuman body in an environment having no washing facilities. In addition,there is a possibility that when taking such a print, clothes will bestained with ink or India ink, so suitable preparation is neededbeforehand.

Furthermore, the number of persons having sensitive skin or allergies isincreasing, so that there is apprehension about the influence ofchemicals contained in ink on the skin. Particularly, when taking infanthandprints or footprints, ink for obtaining prints of a hand or footrequires high safety.

SUMMARY OF THE INVENTION

The present invention has been made in view of the circumstancesmentioned above. Accordingly, it is an object of the present inventionto provide a method that makes it easy to obtain a handprint, afootprint, a fingerprint, etc., without being limited to time, location,or physical constitution. Another object of the invention is to providea set and apparatus for taking such a print by the method.

The method of the present invention is a method of obtaining prints ofthe shape or patterns of at least a part of a human body. The print ofthe shape refers to a print representing the contours of a human body.Examples are a handprint, a footprint, etc. The print of the patternsmeans a print that represents irregularities on the skin surface of ahuman body. Examples are fingerprints, lines in the palm of a hand, etc.

The method of the present invention utilizes specific opticalcharacteristics resulting from the surface structure of a recordingmedium to take the print of a part of a human body. More specifically,in accordance with the present invention, there is provided a method ofobtaining prints of the shape and/or patterns of at least a part of ahuman body. The method comprises a step of causing the aforementionedpart to contact a surface layer of a recording medium, over which aplurality of metallic grains with an outside size of 200 nm or less aredistributed, and a step of causing secretions from a skin surface of theaforementioned part to adhere to the surface layer of the recordingmedium to take the aforementioned print. In a recording medium that hasthe aforementioned surface structure, the reflection characteristics oflight at a region having secretions changes considerably. For thisreason, if only secretions are caused to adhere to the recording medium,a print visible to the eyes of an observer can be recorded.

The aforementioned outside size refers to the size of the largest partof the metallic grain. For instance, if the metallic grain is a sphereor an ellipsoid, the outside size refers to the diameter. Also, if themetallic grain is a rectangular parallelepiped, the outside size refersto the height or width.

In the method of the present invention, the surface layer of therecording medium is preferably a layer in which the metallic grains areprovided in alumina minute holes obtained by anodizing a material thatcontains aluminum as its main component. The minute holes, naturallyformed when aluminum or an aluminum alloy is anodized, are arranged withhigh regularity. Therefore, if metallic grains are provided in theminute holes, the metallic grains are also arranged with highregularity.

In the method of the present invention, the surface layer is preferablycoated with a layer having a refractive index different from that ofsecretions, after the secretions adhere to the surface layer of therecording medium. In this case, since the secretions are isolated fromair, it is prevented from decomposing or being wiped off. Thus,long-term storage of the recording medium becomes possible.

In addition, a print taken by the aforementioned method maybe stored asdigital image, by optically reading the recording medium after thesecretion adheres to the surface layer of the recording medium, thengenerating a digital image representing an adhesion status of thesecretion, and storing the digital image on a predetermined storagemedium.

In accordance with the present invention, there is provided a printtaking set. The set comprises a recording medium in which a plurality ofmetallic grains with an outside size of 200 nm or less are distributedover a surface layer, and a coating member. The coating member can beapplied to or stuck on the surface layer of the recording medium, andcomprises a material that has a refractive index different from anyrefractive index of secretions from a human skin. The material of thecoating member doesn't matter if it can fix secretions adhering to therecording medium so that the secretions are isolated from air. It ispreferably a sheet member, but may be a coating fluid that hardens whendried.

In accordance with the present invention, there is provided a printtaking apparatus. The apparatus comprises a recording medium imagegeneration means, and data storage means. In the recording medium, aplurality of metallic grains with an outside size of 200 nm or less aredistributed over the surface layer. The image generation means is usedfor optically reading out the recording medium and generating a digitalimage representing an adhesion status of a substance to the recordingmedium. The data storage means is used for storing the generated digitalimage on a predetermined data storage medium.

The print taking method of the present invention does not require ink orIndia ink, because the print of a hand or a foot is recorded on arecording medium by making use of specific optical characteristicsresulting from the surface structure of the recording medium. For thisreason, handprints, footprints, etc., can be easily taken regardless ofthe presence or absence of washing facilities, clothes, and physicalconstitution. In addition, the recording medium can be reused ifsecretions are removed therefrom, and consequently, prints can be easilyretaken.

The print taking set of the present invention comprises theaforementioned recording medium and a member for coating the recordingmedium. Since the recording medium can be coated immediately after aprint is taken, the taken print can be stored in an optimal state.

The print taking apparatus of the present invention optically reads aprint taken by the aforementioned method and stores the print as adigital image. Thus, the recording medium can be reused if secretionsare removed therefrom. The taken print can also be processed orreproduced as a digital image.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in further detail with referenceto the accompanying drawings wherein:

FIG. 1 is a perspective view showing a recoding medium fabricated inaccordance with a first embodiment of the present invention;

FIG. 2 is a sectional view of the layer structure of the recordingmedium shown in FIG. 1;

FIG. 3 is a plan view showing the recording medium, to which secretionsadhere;

FIG. 4 is a sectional view of the recording medium shown in FIG. 3;

FIG. 5 is a graph showing the intensity of reflected light due to alocal plasmon resonance phenomenon;

FIG. 6 is a sectional view showing a recoding medium fabricated inaccordance with a second embodiment of the present invention;

FIG. 7 is a perspective view of a print taking set of the presentinvention that employs the recording medium shown in FIG. 1; and

FIG. 8 is a block diagram of a print taking apparatus of the presentinvention that employs the recording medium shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now in greater detail to the drawings and initially to FIG. 1,there is shown a recording medium 1 fabricated in accordance with afirst embodiment of the present invention. As shown in the figure, therecording medium 1 comprises an aluminum substrate 2, an alumina layer 3obtained by anodizing the aluminum substrate 2, and gold grains 5 heldin minute holes 4 formed in the surface of the alumina layer 3. Therecording medium 1 can be formed into an arbitrary size, depending onthe type of print that is to be taken. Only part of the recording medium1 is shown in FIG. 1.

FIG. 2 shows a sectional view of the layer structure shown in FIG. 1. Inthis embodiment, the minute hole 4 is 200 nm in depth and diameter andthe grain diameter of the gold grain 5 in the minute hole 4 is smallerthan 200 nm. The minute holes 4 are disposed at intervals of about 200nm.

The alumina layer 3 is a porous oxide coating and is formed by anodizingthe aluminum substrate 2 in a suitable acid electrolyte. To anodize thesurface of the aluminum substrate 2, the aluminum substrate 2 is fixedto the holder of anodizer and is immersed in an electrolyte within areaction container along the opposite electrode. The electrolyte is, forexample, oxalic acid, phosphoric acid, sulfuric acid, or chromic acidsolution. The electrolyte may be a mixture of acid solutions of two ormore kinds.

Next, a voltage is applied between the aluminum substrate 2 and theopposite electrode. At this time, the aluminum substrate 2 is connectedto the plus side of a power source, while the opposite electrode isconnected to the minus side. When the voltage is applied, first, thealuminum substrate 2 is coated with an oxide layer, and then minuteholes are formed in the oxide layer by the dissolution action of theaforementioned acid solution.

Some of the minute holes 4 grow preferentially with the progress ofanodic oxidation and are arranged at approximately equal spaces. Sincean electric field applied to portions where holes are formed is higherthan that of other portions, dissolution is accelerated at the holedportions and therefore the holes grow in the direction perpendicular tothe surface of the aluminum substrate 2. On the other hand, portionsaround the holes 4 are left on the surface of the alumina layer 3without being dissolved.

The hole diameter, depth, and interval vary depending on anodicoxidation conditions (e.g., the concentration and temperature of anelectrolyte employed in anodic oxidation, voltage-application method,voltage value, time, etc.). The minute holes 4 can be accuratelycontrolled in a range where the interval between minute holes 4 is 10 to500 nm and the hole diameter is 5 to 400 nm. Therefore, if suitableconditions are set, the layer structure shown in FIG. 2 is obtainable.

The minute holes 4 in the alumina layer 3 are arranged with greatregularity, so if the gold grains 5 are respectively arranged in theminute holes, regular arrangement of the gold grains 5 can be obtained.

To arrange the gold grains 5 in the minute holes 4, gold is firstdeposited on the surface in which the minute holes 4 are formed. Then,the gold deposited on around the minute holes 4 is removed so that eachminute hole 4 is filled with the gold grain 5. Instead of deposition,each minute hole 4 may be filled with the gold grain 5 byelectroplating.

Now, a description will be given of how a print is taken by therecording medium 1 described above. As an example, a handprint will betaken as follows.

To take a handprint, a recording medium with a surface area larger thana hand is first prepared. The hand is then impressed on the surface ofthe recording medium 1, that is, the surface in which the gold grains 5are arranged.

At this time, the hand is preferably in a wet state in which sweat orsebum is secreted, not in a dry state. If the hand is dry, sebum orsweat from other parts of the body or saliva is applied to the hand inadvance. If the hand in the wet state is impressed on the surface of therecording medium 1, secretions 7 such as sebum will adhere to ahand-impressed region 6, as shown in FIG. 3.

The present inventors have found that when a print is taken in theabove-described steps with the recording medium 1, clearer contrast isobtained compared with the case where the sebum of a hand is caused toadhere to another medium (e.g., glass). It is considered that the reasonwhy clearer contrast than that of other mediums is obtained is due tothe following reason. That is, the reason is that the wavelength andintensity of light reflected at the surface of the recording medium 1change considerably, depending on specific optical characteristicsresulting from the surface structure of the recording medium 1.

As the specific optical characteristics, there is a local plasmonresonance phenomenon by way of example. The local plasmon resonancephenomenon is a phenomenon where, when light is irradiated to a metallicgrain smaller than the wavelength of the light, free electrons withinthe metallic grain start to vibrate in resonance with the electric fieldof the light. If free electrons start to vibrate, that is, if localplasmon resonance is induced, a strong electric field occurs around ametallic grain and scattering and absorption increase at a specificwavelength (hereinafter referred to as a resonance wavelength). Sincethe resonance wavelength depends on the refractive index of a substancearound a metallic grain, a reflection characteristic varies between thecase where there is some substance around the periphery and the casewhere there is no substance around the periphery. If the refractiveindex of a peripheral substance becomes greater, the resonancewavelength will be shifted to a long wavelength side and lightscattering and absorption will increase.

FIG. 4 shows a sectional view of the boundary between the hand-impressedregion 6 and a hand-unimpressed region. As shown in the figure, in thehand-impressed region 6, the secretion 7 such as sebum adheres to thesurface of the recording medium 1. For this reason, the refractive indexn1 of the secretion 7 on the gold grains 5 is greater than therefractive index n0 of air. When the refractive index n0 of air is 1,the refractive index n1 of the secretion 7 is about 1.45 to 1.47.

FIG. 5 shows the intensity of reflected light obtained when light isirradiated onto the gold grains 5. The horizontal axis represents thewavelength of light, while the vertical axis represents the intensity ofreflected light. In FIG. 5, a broken line indicates the reflectioncharacteristic obtained at an unimpressed region where there are nosecretions, and a full line indicates the reflection characteristicobtained at an impressed region where there are secretions. As shown inthe figure, the resonance wavelength λ1 at an unimpressed region with nosecretion differs from the resonance wavelength λ2 at an impressedregion with secretions. When the secretions are sweat or sebum, thedifference between λ1 and λ2 is 150 nm or so. The intensity of lightreflected at an impressed region is smaller than that at an unimpressedregion.

In practice, the hand of a person has bulging parts and depressed parts,so secretions do not always adhere to a recording medium uniformly.Therefore, there are parts where secretions adhere thickly and partswhere secretions hardly adhere. The intensity of reflected light varieswith the thickness of the secretions. If the secretions adhere thicker,the intensity of reflected light at the thicker part becomes smaller.

If the wavelength of absorbed light varies between an impressed regionto which secretions adhere and an unimpressed region to which nosecretion adheres, the colors of the impressed region and unimpressedregion are visibly different to the naked eye. As previously mentioned,the resonance wavelength varies 150 nm between an impressed region towhich secretions adhere and an unimpressed region to which no secretionadheres, so a clear change in color can be observed. Also, if theintensity of reflected light varies between a thick region to whichsecretions adhere thickly and a thin region to which secretions adherethinly, the irregularities on a skin surface can be discriminated asshades of color on the recording medium 1.

Thus, if only secretions from the skin surface of a human hand is causedto adhere to the recording medium 1, a clear print with relatively greatcontrast can be obtained. It is considered that the reason is due to thesurface structure of the recording medium 1 which can easily induce alocal plasmon resonance phenomenon.

Particularly, when the size of the metal grain is 200 nm or less, aclear print is obtainable. The present invention is not limited to therecording medium 1 shown in FIG. 2. If the sweat or sebum of a humanhand is caused to adhere to a recording medium where a plurality of goldgrains of the aforementioned size are distributed over the entiresurface of the surface layer, a clear print can be similarly obtained.

As shown in FIG. 6, a gold thin film 9 may be formed on a portion of arecording medium surface other than that in which the minute holes 4 areformed. The gold thin film 9 can be formed by depositing gold. At thistime, the distance between the gold thin film 9 and the gold grain 5 ispreferably less than the grain diameter of the gold grain 5. That is,the distance between the top end of the gold grain 5 and the bottom endof the gold thin film 9 is less than the grain diameter of the goldgrain 5. When forming minute holes 4 by anodizing the aluminum substrate2, the depth of the minute holes 4 can be freely adjusted by controllingthe conditions of anodic oxidation. Therefore, at the stage of anodicoxidation, if the depth of the minute holes 4 is set so that thedistance between the gold thin film 9 and the gold grain 5 is less thanthe grain diameter of the gold grain 5, the recording medium 8 shown inFIG. 6 can be fabricated.

In the layer structure shown in FIG. 6, near-field light produced whenlight is irradiated to the gold grains 5 interacts with the gold thinfilm 9, so that an absorption spectrum due to an electric multipoleoccurs. With the synergistic effect between local plasmon resonance andthe electric multipole, a change in reflected light becomes sharper withrespect to a change in the refractive index of a medium around goldgrains. Therefore, it is contemplated that a clearer print can be takenwith the recording medium.

Also, in the case of a recording medium where a plurality of metallicgrains are distributed over the entire surface of the surface layer, theoccurrence of a local plasmon phenomenon is not limited to the casewhere the metallic grains are gold. Therefore, the metal in the minutehole or metal deposited on the surface may be silver (Ag), copper (Cu),or aluminum (Al). Even in cases other than those in which gold isemployed, a recognizable print can be likewise taken. Gold is suitablefor long-term storage, because deposition can be performed at arelatively low temperature and therefore a recording medium is easy tofabricate, and because it is corrosion-resistant. Silver is easilyoxidizable, but is superior in contrast to gold. Also, since copper andaluminum are cheaper than gold and silver, fabrication costs for arecording medium can be reduced. Thus, metals have respectivecharacteristics. Therefore, the material of metallic grains ispreferably selected according to purposes.

In the embodiments shown in FIGS. 1 to 6, regular arrangement of metalgrains is formed by filling minute holes with metal in an anodicoxidation process, but the recording medium used in taking a print canbe fabricated by other methods. For instance, minute holes maybe formedin a substrate and filled with metal by semiconductor fabricationtechniques such as electro-beam lithography. In addition, although thereis a disadvantage that grains are easy to cohere, a recording medium canbe fabricated by a method of immersing the recording medium surface in ametal colloid solution and fixing metal grains in the surface.

That is, the recording medium employed in the print taking method of thepresent invention may be fabricated by any method, as long as metalgrains with an outside size of 200 nm or less are distributed over theentire surface of the surface layer. However, it is most preferable,from the viewpoint of the quality of a print, to fabricate a recordingmedium by a method that arranges metal grains regularly, by making useof the regularity of alumina minute holes formed by anodic oxidation.

In the recording medium employed in the print taking method of thepresent invention, the configuration of the recording medium main bodyis not particularly limited as long as the surface layer is constructedas described above. While the recording media shown in FIGS. 1 and 6 areof a sheet type, they may be a spherical type where metal grains arearranged in the surface of a sphere, or a box type where metal grainsare arranged in each surface of a box.

In a recording medium having secretions such as sebum, it is consideredthat a change in the absorption wavelength and intensity of reflectedlight is mainly caused by light interference and a local plasmonphenomenon. The reason is that when light beams, reflected in two ormore directions due to the influence of secretions on the surface of arecording medium, interfere with each other and light with a specificwavelength is cancelled, a change in color is observed by the naked eye.The present inventors have contemplated that if the surface structure ofa recording medium is determined so that the wavelength cancelled due tointerference and the wavelength due to a local plasmon resonance arealigned or superposed, contrast can be further enhanced compared withthe case where one of the two phenomena is utilized.

Now, a description will be given of how a print is stored. There is apossibility that secretions adhering to a recording medium willdecompose with the lapse of time or will be wiped off by contact with anobject. For this reason, it is preferable that the surface of therecording medium be coated after a print is taken. For example, therecording medium may be covered with a coating sheet, or the recordingmedium surface may be coated with a layer by applying a coating fluidand drying.

A coating member is a member that can prevent secretions, which areadhered to the recording medium from being decomposed and wiped off andhas a refractive index different from that of the secretion. However, ifa coating member meets these conditions, the material of the coatingmember is not particularly limited.

More specifically, a transparent plastic film can be employed as acoating member. Examples of transparent plastic films meeting theabove-described conditions are a transparent film of polyethyleneterephthalate (refractive index 1.65) and a transparent film ofpolycarbonate (refractive index 1.55). In addition, the coating membermay be optical glass. Examples of optical glasses meeting theabove-described conditions are SF-13 (refractive index 1.73 to 1.75) andBaK4 (refractive index 1.56 to 1.57).

By providing a coating, transportation and storage of a recording mediumhaving a print are facilitated. Particularly, when a transparent plasticfilm is used as a coating member, a recording medium is light in weightand easy to handle.

As another method of storing a print, there is a method of opticallyreading a recording medium having a print and then generating a digitalimage representing an adhesion status of the secretion. For instance,reading of a print is performed by irradiating light to a recordingmedium after the print is taken. Then, digital data is acquired for eachpixel by converting the reflected light into an electrical signal with acharge coupled device (CCD), to generate image data. Note that a printtaken on a recording medium by the aforementioned method has a pluralityof colors, unlike a conventional print taken with ink, etc. Therefore,when storing the print as image data, it is desirable to store it as acolor image.

Referring now to FIG. 7, there is shown a print taking set according tothe present invention. As shown in the figure, the print taking set iscomposed of a print taking sheet 10 and a coating sheet 12. The printtaking sheet 10 is constructed of a colored paper sheet or plastic sheetmember on which the recording medium 1 having the layer structure shownin FIG. 2 (recording medium 8 having the layer structure shown in FIG.6) is stuck. The size of the recording medium is smaller than the printtaking sheet 10, and the date the print was taken, a signature, etc.,can be recorded on a blank region 11 of the print taking sheet 10.

The coating sheet 12 is used to protect a print taken on the recordingmedium and is constructed of a coating member such as the aforementionedcoating member. After a print is taken by impressing a human hand on therecording medium 1, the coating sheet 12 is stuck on a region 13indicated by a broken line so as to cover the recording medium 1. Inthis manner, secretions on the recording medium 1 are covered with thecoating sheet 12, so the print taken on the recording medium 1 can besatisfactorily stored. Note that the coating sheet 12 may have an endstuck on the print taking sheet 10 in advance. In this case, theentirety of the coating sheet 12 is stuck on the recording medium 1after a print is taken.

The print taking set of the present invention is easy to carry and doesnot require any special tools when taking a print. In addition, sincethe print is immediately coated, it can be stored in an optimal state.

Referring now to FIG. 8, there is shown a print taking apparatus inaccordance with the present invention. As shown in the figure, the printtaking apparatus is equipped with the aforementioned recording medium 1(or recording medium 8), a reading unit 16, an image processing unit 17,an output control unit 18, and memory 19. The reading unit 16 is used toreceive light reflected from the recording medium 1, convert thereflected light into an electric signal, and generate image data. Theimage processing unit 17 is used to perform a predetermined imageprocess on the image data generated by the reading unit 16. The memory19 is used to store the image data processed by the image processingunit 17. The output control unit 18 is used to output to a display 20the image data processed by the image processing unit 17 or image datastored in the memory 19, and to store these image data in an informationrecording medium, such as a CD-ROM.

The reading unit 16 can employ, for example, a CCD camera. The imageprocessing unit 17, output control unit 18, and memory 19 can berealized by installing a control program for the CCD camera and an imageprocessing program into a general-purpose personal computer.

When taking a print by the print taking apparatus 14, a print is firsttaken by impressing a human hand on the recording medium 1. Then, adigital image representing a substance adhering to the recording medium1 is generated by the reading unit 16 and image processing unit 17. Thegenerated digital image is temporarily stored in the memory 19. That is,the reading unit 16, image processing unit 17, and memory 19 function asimage generation means.

The digital image stored on the memory 19 can be displayed on the screenof the display 20 by the output control unit 18. If there is a defect inthe generated image by viewing the screen, the secretion adhering to therecording medium 1 is removed and a print is retaken. If an appropriateimage is obtained, the output control unit 18 stores the digital imageread out from the memory 19, on a portable recording medium such as aCD-ROM 21 or a hard disk (not shown). Thus, the output control unit 18functions as data storage means.

Since the print taking apparatus of the present invention is constructedas described above, a print taken on the recording medium can be storedand utilized as a digital image. In addition, a print can be retaken anynumber of times until a digital image of a desired picture quality isobtained, so a high-quality print can be always taken.

While the present invention has been described with reference to thepreferred embodiments thereof, the invention is not to be limited to thedetails given herein, but may be modified within the scope of theinvention hereinafter claimed.

1. A method for obtaining prints of the shape and/or patterns of atleast a part of a human body, comprising the steps of: causing said partto contact a surface layer of a recording medium over which a pluralityof metallic grains with an outside size of 200 nm or less aredistributed; and causing secretions from a skin surface of said part toadhere to the surface layer of said recording medium to take said print.2. The method as set forth in claim 1, wherein said surface layer ofsaid recording medium is a layer in which said metallic grains areprovided in alumina minute holes obtained by anodizing a material thatcontains aluminum as its main component.
 3. The method as set forth inclaim 1, wherein said surface layer is coated with a layer having arefractive index different from that of said secretions, after saidsecretions adhere to said surface layer of said recording medium.
 4. Themethod as set forth in claim 1, wherein said recording medium isoptically read after said secretion adheres to said surface layer ofsaid recording medium, a digital image representing an adhesion statusof said secretions is generated, and said digital data is stored on apredetermined storage medium.